Field of the Invention
The disclosed subject matter relates to a method and apparatus for transferring a microstructure from a negative imprint on a nickel shim to an As2S3 optical fiber tip with minimal shape distortion and minimal damage-threshold impacts, thereby improving the anti-reflective properties of the As2S3 optical fiber.
However, the method and apparatus herein presented are not limited in application to As2S3 optical fibers. In fact, the apparatus and method herein presented can be practiced with other optical fiber materials having melting points below 600° C.
Brief Description of Related Art
Optical fibers can be used in a great number of applications in the Mid-IR wavelength region including sensing, imaging and processing. These optical fibers have large refractive indexes, ranging from about 2.3 to about 2.9. Air, on the other hand, has a retractive index of 1. This large difference in refractive index between the optical fibers and air leads to signal losses at the optical fiber/air interface. In some, applications these signal losses at the optical fiber/air interface can amount to 25% or more.
In order to prevent signal losses, some have turned to applying anti-reflective coatings to polished fiber tips. However, polishing can oftentimes lead to optical fiber fracture in delicate fiber materials. Furthermore, anti-reflective coatings often exhibit adhesion problems and rapid degradation as a result of exposure to high intensity signal radiation.